'use strict'
const path = require('path')     //comentjs的导包规则   
const defaultSettings = require('./src/settings.js')   //导入settings.js文件
// 函数    把相对路径转换为绝对路径
function resolve(dir) {
  return path.join(__dirname, dir)   //__dirname  能把当前文件的绝对路径拿到   __dirname===当前文件的绝对路径
}                ///.join(a,b)   能把a和b拼接起来
// 设置settings文件中的title设置  也就是网页的标题名称
const name = defaultSettings.title || 'vue Admin Template' // page title

// 服务器端口号
const port = process.env.port || process.env.npm_config_port || 9528 // dev port

// All configuration item explanations can be find in https://cli.vuejs.org/config/
module.exports = {


  publicPath: '/',   //  '/'是在服务器环境下运行,  './' 是任何环境下运行
  outputDir: 'dist', //  配置打包输出的目录名字
  assetsDir: 'static',  // 配置打包输出的静态资源目录的名字,存放 js  css  img文件
  lintOnSave: process.env.NODE_ENV === 'development',   //是否开启eslint
  productionSourceMap: false,     //是否开启map映射

  // 脚手架静态服务器的配置
  devServer: {
    port: port,   //端口号
    open: true,   //是否自动打开浏览器
    // 错误提示是否在浏览器展示
    overlay: {
      warnings: false,
      errors: true
    },

    // 解决跨域问题 的配置
    proxy: {
      // 如果请求地址以/api打头,就出触发代理机制
      // http://localhost:8888/api/sys/login ->  http://ihrm.itheima.net/api/sys/login
      '/api': {
        target: 'http://ihrm.itheima.net' // 我们要代理的真实接口地址
      }
      // 开启morke服务
      // before: require('./mock/mock-server.js')
    }
  },
  // webpack的对象配置
  configureWebpack: {
    // provide the app's title in webpack's name field, so that
    // it can be accessed in index.html to inject the correct title.
    name: name,
    resolve: {
      alias: {
        '@': resolve('src')
      }
    }
  },
  // webpack函数配置
  chainWebpack(config) {
    // it can improve the speed of the first screen, it is recommended to turn on preload
    config.plugin('preload').tap(() => [
      {
        rel: 'preload',
        // to ignore runtime.js
        // https://github.com/vuejs/vue-cli/blob/dev/packages/@vue/cli-service/lib/config/app.js#L171
        fileBlacklist: [/\.map$/, /hot-update\.js$/, /runtime\..*\.js$/],
        include: 'initial'
      }
    ])

    // when there are many pages, it will cause too many meaningless requests
    config.plugins.delete('prefetch')

    // set svg-sprite-loader
    config.module
      .rule('svg')
      .exclude.add(resolve('src/icons'))
      .end()
    config.module
      .rule('icons')
      .test(/\.svg$/)
      .include.add(resolve('src/icons'))
      .end()
      .use('svg-sprite-loader')
      .loader('svg-sprite-loader')
      .options({
        symbolId: 'icon-[name]'
      })
      .end()

    config
      .when(process.env.NODE_ENV !== 'development',
        config => {
          config
            .plugin('ScriptExtHtmlWebpackPlugin')
            .after('html')
            .use('script-ext-html-webpack-plugin', [{
              // `runtime` must same as runtimeChunk name. default is `runtime`
              inline: /runtime\..*\.js$/
            }])
            .end()
          config
            .optimization.splitChunks({
              chunks: 'all',
              cacheGroups: {
                libs: {
                  name: 'chunk-libs',
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  chunks: 'initial' // only package third parties that are initially dependent
                },
                elementUI: {
                  name: 'chunk-elementUI', // split elementUI into a single package
                  priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
                  test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
                },
                commons: {
                  name: 'chunk-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }
            })
          // https:// webpack.js.org/configuration/optimization/#optimizationruntimechunk
          config.optimization.runtimeChunk('single')
        }
      )
  }
}
